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Analgesics during Pregnancy
Published in “Bert” Bertis Britt Little, Drugs and Pregnancy, 2022
Another narcotic antagonist, naltrexone (Trexan), is also a congener of oxymorphone. Naltrexone is also used in the treatment of opioid dependence, and for weight loss in combination with another drug. The frequency of birth defects after exposure to naltrexone during pregnancy was not increased among 68 infants, but it was unclear exactly when the exposure occurred (Kelty and Hulse, 2017). Importantly, these gravidas were given naltrexone as part of a treatment regimen for heroin addiction. Three case series comprising reportedly unduplicated patients contained 31 infants whose mothers used naltrexone during the first trimester, and there were no congenital anomalies present (Hulse and O’Neil, 2002; Hulse et al., 2001, 2004). According to its manufacturer, this agent was shown to be embryocidal in animal studies. The frequency of birth defects was not increased among rats or rabbits exposed during embryogenesis (McLaughlin et al., 1997).
Biological Approaches
Published in Tricia L. Chandler, Fredrick Dombrowski, Tara G. Matthews, Co-occurring Mental Illness and Substance Use Disorders, 2022
Tricia L. Chandler, Mary C. Hoke, Tara G. Matthews, Elizabeth Reyes-Fournier
Naltrexone is an opioid antagonist used in the treatment of opioid use disorders. Despite its pharmacological qualities, it is also approved to be used as a treatment for alcohol use disorder. Naltrexone has been shown to block opioid receptors, reduce or eliminate the euphoric sensations of opiates and alcohol, and diminish cravings (Lee et al., 2015). Naltrexone, given intramuscularly in a long-acting formulation, is used to eliminate cravings and prevent relapse for individuals with alcohol and/or opiate use disorders (Aboujaoude & Salame, 2016).
Pharmacology of Opioids
Published in Pamela E. Macintyre, Stephan A. Schug, Acute Pain Management, 2021
Pamela E. Macintyre, Stephan A. Schug
Unlike naloxone, naltrexone is effective when given orally. It has a half-life of four hours and its main metabolite is 6-naltrexol, a weaker μ-opioid antagonist but with a half-life of more than 13 hours. Naltrexone (either orally or in the form of a long-acting SC implant or injection) has been used in the treatment of opioid addiction where the effects of a 50-mg oral dose may last up to 24 hours (see Chapter 15). As it is a pure opioid antagonist, it should be stopped at least 24–48 hours before surgery if opioid analgesia is likely to be needed. Caution is required as there is some evidence to suggest that, after cessation, patients may become very sensitive to opioids.
Efficacy of Extended-Release Injectable Naltrexone on Alcohol Use Disorder Treatment: A Systematic Review
Published in Journal of Psychoactive Drugs, 2023
Satish K. Kedia, Nikhil Ahuja, Patrick J. Dillon, Andrew Jones, Santosh Kumar, Sanjaya Satapathy
Multiple studies indicate that oral naltrexone is effective in limiting alcohol cravings, reducing days of drinking (including heavy drinking), and decreasing the chances of relapse, especially when used in conjunction with behavioral interventions (Lee et al. 2010). Naltrexone is also available in injectable microsphere form; marketed commercially as Vivitrol®, it is administered as an intramuscular injection (380 mg) and includes proprietary active moieties that facilitate extended release of naltrexone in the body over 28 days (Garbutt 2009; Mannelli et al. 2007). In injectable form, naltrexone has been shown to have long-lasting blocking effects on opioid receptors in the brain, thereby reducing alcohol cravings (Mannelli et al. 2007). Some studies reported that naltrexone’s effects may last beyond treatment completion and extend up to 1 year (Edelman et al. 2019; Lee et al. 2012); other studies, however, stated that its positive benefit is diluted after a few months (Longabaugh et al. 2009; Roozen, de Waart, and van den Brink 2007).
Opioid harm reduction: A scoping review of physician and system-level gaps in knowledge, education, and practice
Published in Substance Abuse, 2022
Emma Gugala, Owanate Briggs, Leticia R. Moczygemba, Carolyn M. Brown, Lucas G. Hill
Three MOUD agents are FDA-approved for the treatment of opioid use disorder (OUD): buprenorphine, methadone, and naltrexone. Each is recommended as part of a comprehensive treatment plan which includes counseling and other behavioral therapies. Buprenorphine is an opioid partial agonist that is proven effective for the treatment of OUD. Access to buprenorphine is typically prescribed from office-based settings, but it is also administered in hospitals and inpatient addiction treatment facilities.8 Methadone, an opioid agonist, has also been associated with reductions in all-cause mortality.5 Access to methadone is managed through SAMHSA’s Accredited and Certified Opioid Treatment Program (OTP), which grants dispensing authority to qualified practitioners.9 OTPs are highly regulated facilities and the only setting in which patients can access methadone for ongoing treatment, though it can also be administered in hospitals and inpatient addiction treatment facilities. Naltrexone, a long-acting opioid antagonist, inhibits the sedative and euphoric effects of opioids, and it can be administered by any medical practitioner licensed to prescribe medication.10 However, unlike buprenorphine and methadone, naltrexone requires abstinence from opioids, and therefore cannot be classified as a harm reduction strategy.
Naltrexone at low doses (LDN) and its relevance to cancer therapy
Published in Expert Review of Anticancer Therapy, 2022
Naltrexone is an opiate receptor antagonist preventing opiate stimulation; it has been used for decades as a treatment for addiction to opiates as it prevented the euphoria induced by recreational use of morphine and heroin [1,2]. Mechanistically, naltrexone interfered physically with the interaction between opiate and receptor, and by doing so neutralized their action [2]. In reality, however, opiate receptor expression in cells is both complex and malleable, and repeated and chronic stimulation/blockade by naltrexone could lead to changes in the expression and distribution of the receptors. Indeed, in some instances, blocking these receptors to negate opiate action could actually result in a compensatory increase in other receptors [3]. This introduces the interesting possibility that a key ‘MOA’ for naltrexone could actually be to increase the expression of related receptors. However, this could also pose a concern; not only would complicate the treatment of addiction for which naltrexone was initially used but these receptors could provide new targets for other ligands. The implication would be using naltrexone to counteract opiate addiction could unintentionally increase the action of endogenous ligands. It is thus conceivable that naltrexone could influence more than just disorders of addiction. Of particular note, and relevance to the current review, endogenous opioids were reported to be able to influence the immune system to enough of an extent to be considered as immune modulators and a role as immunotherapy was initially considered in the early 1980s [4].